Thyroid cancer is the most rapidly increasing cancer in the United States, with an annual percentage increase of 4.5% in women and 5.3% in men. High-risk thyroid cancer can be effectively treated by radioactive iodine, which leads to improved survival and decreased recurrence rates. The successful treatment of thyroid cancer has lead to an ever-increasing number of thyroid cancer survivors, many of whom are young. However, in addition to destroying thyroid cancer, radioactive iodine also damages salivary tissue, causing discomfort and swelling, recurrent salivary infections, decreased ability to taste, difficulty chewing dry foods, salivary gland stones, and increased dental caries. These side effects negatively impact quality of life. Despite recognition of salivary symptoms, risk factors and correlation with salivary function are less understood and represent knowledge gaps. Recently, additional craniofacial consequences of RAI treatment have been recognized. Lacrimal symptoms include dry eyes, over-flowing tears, and conjunctivitis. Nasal symptoms include nasal irritation, dry nose, and nose bleeds. The true incidence and consequences of lacrimal and nasal damage are unknown. Measurement of the range and impact of craniofacial side effects is essential before we can develop techniques to minimize RAI-related morbidity. We will develop and evaluate a patient-reported questionnaire of salivary, lacrimal and nasal symptoms in patients with differentiated thyroid cancer who are treated with radioactive iodine. We will use a mixed methods approach to develop the questionnaire (called SALANS) through two linked phases of research. In Phase I, we will conduct focus groups with 48 patients with thyroid cancer treated with radioactive iodine to identify the craniofacial symptoms and understand how these symptoms impact patients' quality of life. Following qualitative analyses and expert review of items, we will conduct cognitive testing of the newly designed SALANS questionnaire in 16 patients. After revision, we will conduct a pilot test of the SALANS questionnaire with a group of 80 patients with thyroid cancer (n=50 treated with radioactive iodine; n=30 not treated with radioactive iodine) to establish dimensionality and construct and discriminant validity. In Phase II, we will conduct a prospective cohort study with 50 patients newly diagnosed with differentiated thyroid cancer who will receive radioactive iodine treatment. We will conduct assessments prior to and then 7-days and 3, 6, 9 and 12 months post radioactive iodine therapy. We will correlate SALANS scores with objective measures of salivary function using salivary flow, performing salivary scintigraphy, and measurement of serum salivary amylase. The long-term goal of this research is to provide a valid and reliable questionnaire that can serve as the underpinning for future studies to prevent or ameliorate craniofacial damage in patients receiving radioactive iodine therapy.